Thrombectomy devices employing a thrombus capture body and a thrombus blocking body are known from U.S. Pat. Nos. 6,695,858 and 7,220,269 and comprise an elongated catheter member having a distal part and a proximal part, a thrombus blocking body disposed on the distal part of the catheter member and radially expansible between a contracted orientation and an expanded, thrombus-blocking, orientation, a thrombus capture body disposed on the distal part of the catheter member in an axially spaced-apart relationship to the thrombus blocking body, and radially expansible between a contracted orientation and an expanded, thrombus-capture, orientation having an open leading end for receipt of thrombus, deployment means actuable to deploy and retract the thrombus capture body and thrombus blocking body, and control means operable to provide relative movement between the thrombus capture body and the thrombus blocking body. Specifically, the actuation means of these devices is designed to maintain the thrombus capture body in a stationary position, while moving the thrombus blocking body towards the thrombus capture body. While these devices have shown limited success with removal of short thrombus from blood vessels, they do not adequately remove longer thrombus. This problem is illustrated in Comparative FIGS. 14A and 14B, which shows a blood vessel B containing a long thrombus C, and a device of the prior art located for removal of the thrombus. Actuation of the device causes the blocking member D to move in the direction of arrow E (FIG. 14A), while the thrombus capture body F remains stationary. It can be seen from FIG. 14B that, due to the length of the thrombus C, movement of the thrombus blocking member D does not translate to thrombus being pushed into the capture body F, but rather causes the thrombus C to clog up. US 2011/0202088 describes a similar thrombectomy device to those described above. FIG. 13 of this document describes a device having a distal collapsible collector assembly 412 that in use is pulled towards the proximal collector assembly 416. A problem associated with this device is that the circumferential edge of the collector 412 would catch on any obstacles causing the collector to flare.
US2002/0010487 describes an expansible shearing catheter for thrombus removal. In one embodiment (FIG. 25), the device comprises an expansible occlusion member located distally of the shearing basket that is configured to prevent flow downstream beyond the occlusion member and is located a distance distally of the thrombus. Treatment of the lesion involves pushing the shearing catheter downstream towards and into contact with the thrombus, where the action of the outer basket and inner rotating basket cause the break-up of the thrombus. The use of this embodiment does not involve compression of thrombus between the occlusion body and shearing basket; rather, the occlusion body is located during use a distance from the thrombus and functions to occlude blood flow downstream of the thrombus.
It is an object of the invention to overcome at least one of these problems.